Go: fatal error: concurrent map writes
fatal error: concurrent map writes
goroutine 12 [running]:
runtime.throw(0x1, 0x0)
Immediate Remediation
go
var mu sync.Mutex mu.Lock() m[key] = val mu.Unlock()
Root Cause Analysis
Go maps are not safe for concurrent writes. When multiple goroutines mutate the same map without synchronization, the runtime detects the race and aborts with a fatal error to prevent memory corruption.
Verification & Guardrails
- Run `go run -race` to catch data races before they become fatal.
- For read-heavy workloads, consider using sync.Map or sharding by key instead of a single mutex.
- Concurrent reads are safe; the error requires at least one writer and one other goroutine accessing the map.
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